Currently, some electronic devices such as tablet computer, smart phone and so on all have a projection function, a projection assembly is provided in these electronic devices having the projection function, so that the user can use these electronic devices to achieve the projection function. When using the projection function, the user can directly project an interface displayed on an electronic device having the projection function onto a wall, a desktop, or a projector screen, see FIG. 1-1, the tablet computer can project its display interface onto a wall. When using the projection function, the user can also connect one electronic device having the projection function to another electronic device that generally has a larger display screen, for example, a smart phone having the projection function can be connected to an LCD TV, so that a display interface of the smart phone is displayed via the LCD TV, as such, the user projects the display interface onto a larger display screen, which can get better visual viewing experience.
However, due to shape limits of the mobile phone or tablet computer and other electronic devices per se, it needs to adopt a holder or other means to support during the projection; and the user needs to manually adjust the projected screen to maintain the projected screen horizontal, such manual adjustment manner depends on personal viewing locations, usage preferences etc., it is troublesome and is apt to cause error.